1. Field of the Invention
The present invention relates to a fuel supply system for a boat and an outboard motor. Specifically, the present invention relates to a fuel supply system for a boat having a fuel supply pump and an outboard motor. The fuel supply pump supplies the fuel reserved in a second fuel tank connected to a first fuel tank mounted on a hull to a fuel injection device.
2. Description of the Related Art
Conventionally, a fuel supply system for a boat having a fuel supply pump that supplies the fuel reserved in a second fuel tank connected to a first fuel tank mounted on a hull to a fuel injection device is known (see JP-A-2001-152896, for example).
The fuel supply system for a boat described in JP-A-2001-152896 is a fuel supply system for a boat employed for an outboard motor. In JP-A-2001-152896, fuel pumped from a fuel tank (first fuel tank) mounted on a hull is reserved in a vapor separator tank (second fuel tank). The fuel reserved in the vapor separator tank is supplied to a fuel injection device by a fuel supply pump. Also, in JP-A-2001-152896, there is provided a so-called in-tank fuel supply pump that is disposed in the vapor separator tank.
In general, a fuel supply pump generates negative pressure to draw fuel therein. However, when negative pressure is generated in order to draw fuel, the fuel may boil under reduced pressure due to the negative pressure. In this case, the fuel becomes vapor, generating bubbles in the fuel supply pump. If bubbles occur in the fuel supply pump, normal fuel transportation will be hampered. Thus, if vapor exists in the fuel supply pump during engine starting, it is difficult to properly transport fuel to a fuel injection device due to the vapor in the fuel supply pump. Therefore, it is necessary to discharge vapor from the fuel supply pump. Accordingly, it takes time to discharge the vapor from the fuel supply pump during engine starting, resulting in deterioration in engine startability.